Films having high hermeticity and a low dielectric constant can be used as copper diffusion barrier films, etch stop films, CMP stop films and other hardmasks during IC fabrication. Hermetic films can protect the underlying layers, such as layers of metal and dielectric, from exposure to atmospheric moisture and oxygen, thereby preventing undesirable oxidation of metal surfaces and absorption of moisture by a dielectric. Specifically, a bi-layer film having a hermetic bottom layer composed of hydrogen doped carbon and a low dielectric constant (low-k) top layer composed of low-k silicon carbide (e.g., high carbon content hydrogen doped silicon carbide) can be employed. Such bi-layer film can be deposited by PECVD methods on a partially fabricated semiconductor substrate having exposed layers of dielectric and metal.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of forming a copper diffusion barrier film in a semiconductor device, the method comprising: (a) receiving a semiconductor substrate comprising an exposed dielectric layer; (b) forming a hermetic hydrogen doped carbon layer on at least a portion of the exposed dielectric layer, wherein the hermetic hydrogen doped carbon layer consists essentially of carbon and hydrogen; and (c) forming a hydrogen doped silicon carbide layer on the hydrogen doped carbon layer, wherein together the hydrogen doped silicon carbide layer and the hydrogen doped carbon layer serve as the copper diffusion barrier film, and wherein said copper diffusion barrier film has an effective dielectric constant of less than about 4.0.
2. The method of claim 1 , wherein in (a) the semiconductor substrate further comprises exposed copper lines or interconnects and the semiconductor substrate provides a substantially planar surface.
3. The method of claim 2 , further comprising forming a PSAB capping layer on at least some of the exposed copper lines or interconnects prior to operation (b).
4. The method of claim 3 , wherein forming the PSAB capping layer comprises transforming a top portion of exposed copper by reacting copper atoms with a first reactant selected from the group consisting of SiH 4 , GeH 4 , PH 3 , B 2 H 6 , AsH 3 , H 2 S, H 2 Se, H 2 Te, CH 4 , and C x H y to afford a layer of material selected from the group consisting of Cu x Si y , Cu x Ge y , Cu x P y , Cu x B y , Cu x As y , Cu x S y , Cu x Se y , Cu x Te y , and Cu x C y .
5. The method of claim 4 , wherein forming the PSAB capping layer further comprises contacting the layer of material selected from the group consisting of Cu x Si y , Cu x Ge y , Cu x P y , Cu x B y , Cu x As y , Cu x S y , Cu x Se y , Cu x Te y and Cu x C y with a second reactant selected from the group consisting of N 2 , NH 3 , CH 4 , C 2 H 4 , C 2 H 2 , C x H y , a gas from the family of methyl-substituted silanes, a gas from the family of methyl-substituted amines and HMDS, to afford a material selected from the group consisting of nitrogen (N), carbon (C) or silicon (Si) doped Cu x Si y , Cu x Ge y , Cu x P y , Cu x B y , Cu x As y , Cu x S y , Cu x Se y , Cu x Te y and Cu x C y .
6. The method of claim 5 , wherein the first reactant is SiH 4 , the second reactant is NH 3 , and the formed PSAB layer comprises Si x N y .
7. The method of claim 3 , wherein forming the PSAB capping layer comprises plasma enhanced chemical vapor deposition (PECVD).
8. The method of claim 7 , wherein the PSAB capping layer is formed at a temperature of less than 300° C.
9. The method of claim 1 , wherein operation (b) is performed by a PECVD process.
10. The method of claim 1 , wherein operation (b) comprises: providing the semiconductor substrate in a deposition chamber; exposing the substrate to a process gas comprising a hydrocarbon precursor gas having a partial pressure between about 0.01 and 4 Torr; depositing the hydrogen doped carbon layer on at least a portion of the exposed dielectric layer by a PECVD process using a dual frequency RF (LF and HF) power in which LF:HF ratio is at least about 2:1.
11. The method of claim 10 , wherein the hydrogen doped carbon layer is formed at a process temperature of between about 30 and 300° C.
12. The method of claim 10 , wherein the process gas further comprises hydrogen gas and helium gas.
13. The method of claim 1 , wherein the layer of hydrogen doped silicon carbide has a composition of at least 40% carbon.
14. The method of claim 1 , wherein the layer of hydrogen doped silicon carbide is formed by a PECVD process.
15. The method of claim 14 , wherein the PECVD uses a silicon carbide precursor selected from the group consisting of tetramethylsilane, ethynyltrimethylsilane, vinylphenylmethylsilane, phenyldimethylsilane, tri-iso-propylsilane, 3-(trimethylsilyl)cyclopentene, vinylphenyldimethylsilane, and vinyldimethylsilane.
16. The method of claim 15 , wherein the PECVD uses a silicon carbide precursor selected from the group consisting of ethynyltrimethylsilane, vinylphenylmethylsilane, phenyldimethylsilane, tri-iso-propylsilane, 3-(trimethylsilyl)cyclopentene, vinylphenyldimethylsilane and vinyldimethylsilane.
17. The method of claim 15 , wherein the PECVD uses a silicon carbide precursor selected from the group consisting of ethynyltrimethylsilane, 3-(trimethylsilyl)cyclopentene, and vinyldimethylsilane.
18. The method of claim 14 , wherein PECVD uses a silicon carbide precursor having a composition with a C:Si ratio of at least 2:1.
19. The method of claim 14 , wherein PECVD uses a silicon carbide precursor having a composition with a C:Si ratio of at least 3:1.
20. The method of claim 1 , wherein, wherein the copper diffusion barrier film has a hermeticity defined by a stress shift of tensile TEOS underlying the film, of less than 10 MPa.
21. The method of claim 1 , wherein the hydrogen doped carbon layer has a thickness of about 10-10000 Å.
22. The method of claim 1 , wherein the hydrogen doped silicon carbide layer has a thickness of about 10-10000 Å.
23. The method of claim 1 , wherein operations (b) and (c) are performed at different stations of a multi-station apparatus.
24. The method of claim 3 , wherein formation of the PSAB layer and operation (b) are performed at one station of a multi-station apparatus and operation (c) is performed at a different station of the multi-station apparatus.
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February 22, 2007
March 29, 2011
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